Method for manufacturing an electronic module, and an electronic module

ABSTRACT

This publication discloses an electronic module and a method for manufacturing an electronic module, in which a component ( 6 ) is attached to the surface of a conductive layer and electrical and electrical contacts are formed between the contact zones of the component ( 6 ) and the conductive layer. After this, an insulating-material layer ( 1 ), which surrounds the component ( 6 ) attached to the conductive layer, is formed on, or attached to the surface of the conductive layer. After this, conductive patterns ( 14 ) are formed from the conductive layer, to which the component ( 6 ) is attached.

The present invention relates to an electronic module and a method formanufacturing the electronic module.

In particular, the invention relates to an electronic module, whichincludes one or more components embedded in an installation base. Theelectronic module can be a module like a circuit board, which includesseveral components, which are connected to each other electrically,through conducting structures manufactured in the module. The componentscan be passive components, microcircuits, semiconductor components, orother similar components. Components that are typically connected to acircuit board form one group of components. Another important group ofcomponents are components that are typically packaged for connection toa circuit board. The electronic modules to which the invention relatescan, of course, also include other types of components.

The installation base can be of a type similar to the bases that aregenerally used in the electronics industry as installation bases forelectrical components. The task of the base is to provide componentswith a mechanical attachment base and the necessary electricalconnections to both components that are on the base and those that areoutside the base. The installation base can be a circuit board, in whichcase the construction and method to which the invention relates areclosely related to the manufacturing technology of circuit boards. Theinstallation base may also be some other base, for example, a base usedin the packaging of a component or components, or a base for an entirefunctional module.

The manufacturing techniques used for circuit boards differ from thoseused for microcircuits in, among other things, the fact that theinstallation base in microcircuit manufacturing techniques, i.e. thesubstrate, is of a semiconductor material, whereas the base material ofan installation base for circuit boards is some form of insulatingmaterial. The manufacturing techniques for microcircuits are alsotypically considerably more expensive that the manufacturing techniquesfor circuit boards.

The constructions and manufacturing techniques for the cases andpackages of components, and particularly semiconductor components differfrom the construction and manufacture of circuit boards, in thatcomponent packaging is primarily intended to form a casing around thecomponent, which will protect the component mechanically and facilitatethe handling of the component. On the surface of the component, thereare connector parts, typically protrusions, which allow the packagedcomponent to be easily set in the correct position on the circuit boardand the desired connections to be made to it. In addition, inside thecomponent case, there are conductors, which connect the connector partsoutside the case to connection zones on the surface of the actualcomponent, and through which the component can be connected as desiredto its surroundings.

However, component cases manufactured using conventional technologydemand a considerable amount of space. As electronic devices have grownsmaller, there has been a trend to eliminate component cases, which takeup space, are not essential, and create unnecessary costs. Variousconstructions and methods have been developed to solve this problem.

One known solution is flip-chip (FC) technology, in which non-packagedsemiconductor components are installed and connected directly to thesurface of the circuit board. However, flip-chip technology has manyweaknesses and difficulties. For example, the reliability of theconnections can be a problem, especially in applications, in whichmechanical stresses arise between the circuit board and thesemiconductor component. In an attempts to avoid mechanical stresses, asuitable elastic underfill, which equalizes mechanical stresses, isadded between the semiconductor component and the circuit board. Thisprocedural stage slows down the manufacturing process and increasescosts. Even the thermal expansion caused by the normal operation of adevice may cause mechanical stresses large enough to compromise thelong-term reliability of an FC structure.

U.S. Pat. No. 4,246,595 discloses one solution, in which recesses areformed in the installation base for the components. The bottoms of therecesses are bordered by an insulation layer, in which holes are madefor the connections of the component. After this, the components areembedded in the recesses with their connection zones facing the bottomof the recess, electrical contacts being formed to the componentsthrough the holes in the insulation layer. In such a method, problemscan arise, for instance, when aligning the feed-throughs with thecontact zones of the component. This is because the feed-throughs mustbe aligned relative to components lying under the insulation layer. Inother ways too, the method does not correspond to the technology usednowadays (the patent dates from 1981).

JP application publication 2001-53 447 discloses a second solution, inwhich a recess is made for the component in the installation base. Thecomponent is placed in the recess, with the component's contact zonesfacing towards the surface of the installation base. Next, an insulationlayer is made on the surface of the installation base and over thecomponent. Contact openings for the component are made in the insulationlayer and electrical contacts are made to the component, through thecontact openings. In this method too, the alignment of the feed-throughswith the contact zones of the component can cause problems, as thealignment must be made relative to a component lying under theinsulation layer. In the method, considerable accuracy is demanded inmanufacturing the recess and setting the component in the recess, sothat the component will be correctly positioned, to ensure the successof the feed-throughs, relative to the width and thickness of theinstallation board.

In general too, the connection of components through feed-throughs madein the insulation layer creates a challenge to techniques, in which anattempt is made to embed components inside a circuit board or otherinstallation base. Problems can arise, for example, due to the alignmentprecision, the stress created on the surface of the component by themanufacture of the hole, and by the covering of the edge areas of thefeed-through by conductive material. Even a partial reduction of theproblems relating to feed-throughs would be beneficial to the low-costmanufacture of reliable electronic modules that include unpackagedcomponents embedded in an installation base. On the other hand,embedding a component inside an installation base will allow theconstruction to better withstand mechanical stress, which has been aproblem in flip-chip technology.

The invention is intended to create a method, with the aid of whichunpackaged components, such as semiconductor components and particularlymicrocircuits, can be attached and connected reliably and economicallyto their installation base.

The invention is based on the component being attached to the surface ofa conductive layer and electrical contacts being formed between theconductive layer and the contact zones of the component. An ultrasonicor thermo-compression methods, which are capable of formingmetallurgical joints, are used to attach the components to the surfaceof the conductive layer. After this, an insulating-material layer, whichsurrounds the component attached to the conductive layer, is formed on,or attached to the surface of the conductive layer. After this,conductive patterns are formed from the conductive layer, to which thecomponent is attached.

More specifically, the method according to the invention ischaracterized by what is stated in claim 1.

With the method according to the invention, it is possible tomanufacture numerous different electronics module embodiments. One suchelectronic module embodiment is characterized by what is stated in claim20. The characterizing features of another possible electronic moduleembodiment are, in turn, defined in claim 21. It is also possible tomanufacture differing electronics modules with the aid of the method.

Considerable advantages are gained with the aid of the invention. Thisbecause it is possible, with the aid of the invention, to manufacturereliable and economical electronic modules, which include unpackagedcomponents embedded in an installation base.

Because the components can be embedded inside the installation base, inpreferred embodiments it is possible to achieve a reliable andmechanically durable construction.

With the aid of the invention, it is also possible to reduce the numberof the problems that appear in the prior art, which are caused by thefeed-throughs relating to connecting the components. This is because theinvention has embodiments, in which there is no need at all to makefeed-throughs, the components being instead connected, already in theinstallation stage, to the conductor membrane, from which the conductorsleading to the components of the electronic module are made.

In the embodiments, an installation base, which can be a circuit board,is manufactured around the components attached to the conductive layer.Thus the components, of which there may be one or several, becomeembedded and connected as desired to the base construction beingmanufactured.

In the embodiments of the invention, it is thus possible to manufacturea circuit board, inside which components are embedded. The inventionalso has embodiments, with the aid of which a small and reliablecomponent package can be manufactured around a component, as part of thecircuit board. In such embodiments, the manufacturing process is simplerand cheaper that manufacturing methods in which separate casedcomponents are installed and connected to the surface of the circuitboard. The manufacturing method can also be applied to use the method tomanufacture Reel-to-Reel products. Thin and cheap circuit-board productscontaining components can be made by using the methods according to thepreferred embodiments.

The invention also permits many other preferred embodiments, which canbe used to obtain significant additional advantages. With the aid ofsuch embodiments, a component's packaging stage, the circuit board'smanufacturing stage, and the assembly and connecting stage of thecomponents, for example, can be combined to form a single totality. Thecombination of the separate process stages brings significant logisticaladvantages and permits the manufacture of small and reliable electronicmodules. A further additional advantage is that such anelectronic-module manufacturing method can mostly utilize knowncircuit-board manufacturing and assembly technologies.

The composite process according to the embodiment referred to above is,as a totality, simpler that manufacturing a circuit board and attachinga component to the circuit board using, for example, the flip-chiptechnique. By using such preferred embodiments, the following advantagesare obtained, compared to other manufacturing methods:

Soldering is not needed in the connections of the components, instead anelectrical connection between the connection zones on the surface of thecomponent and the metal membrane of the installation base is created,for example, by ultrasonic welding, thermo-compression, or some othersuch method, in which the temperatures required to achieve electricalconnections, though high, are of short duration and local, and in whichhigh temperatures are not required over a wide area. This means that theconnection of a component does not need metal being maintained moltenfor a long time with its associated high temperature. Thus, theconstruction is made more reliable than soldered connections.Particularly in small connections, the brittleness of the metal alloyscreate large problems. In a solderless solution according to a preferredembodiment, it is possible to achieve clearly smaller constructions thanin soldered solutions. The manufacturing method can even be designed sothat, during the connection process of a component, heat is brought onlyto the area of the connection, so that the areas most strongly heatedare the connection zone of the component and the area to which thecomponent is connected. Elsewhere in the structure the temperatureremains low. This gives greater freedom of choice when selecting thematerials of the installation base and the components. If ultrasonicwelding is used as the connection method, higher temperatures may onlybe required to harden the fillers used. Polymer membranes, which arehardened other than through the effect of heat, for example, chemicallyor with the aid of electromagnetic radiation, such as UV light, can alsobe used in the method. In such a preferred embodiment of the invention,the temperature of the installation base and components can be kept verylow during the entire process, for example, at less than 100° C.

As smaller structures can be manufactured using the method, thecomponents can be placed closer together. Thus, the conductors betweenthe components also become shorter and the characteristics of theelectronic circuits improve. For example, losses, interferences, andtransit-time delays can be significantly reduced.

The method permits a lead-free manufacturing process, which isenvironmentally friendly.

When using a solderless manufacturing process, fewer undesirableintermetallics also arise, thus improving the long-term reliability ofthe construction.

The method also permits three-dimensional structures to be manufactured,as the installation bases and the components embedded in them can bestacked on top of each other.

The invention also permits other preferred embodiments. For instance,flexible circuit boards can be used in connection with the invention.Further, in embodiments, in which the temperature of the installationbase can be kept low during the entire process, organic manufacturingmaterials can be used comprehensively.

With the aid of embodiments, it is also possible to manufactureextremely thin structures, in which, despite the thinness of thestructure, the components are entirely protected inside theirinstallation base, such as a circuit board.

In embodiments, in which the components are located entirely inside theinstallation base, the connections between the circuit board and thecomponents will be mechanically durable and reliable.

The embodiments also permit the design of electronic-modulemanufacturing processes requiring relatively few process stages.Embodiments with fewer process stages correspondingly also require fewerprocess devices and various manufacturing methods. With the aid of suchembodiments, it is also possible in many cases to cut manufacturingcosts compared to more complicated processes.

The number of conductive-pattern layers of the electronic module canalso be chosen according to the embodiment. For example, there can beone or two conductive-pattern layers. Additional conductive-patternlayers can be manufactured on top of these, in the manner known in thecircuit-board industry. A total module can thus incorporate, forexample, three, four, or five conductive-pattern layers. The verysimplest embodiments have only one conductive-pattern layer and indeedone conductor layer. In some embodiments, each of the conductor layerscontained in the electronic module can be exploited when formingconductive patterns.

In embodiments, in which the conductor layer connected to a component ispatterned only after the connection of the component, the conductorlayer can include conductor patterns even at the location of thecomponent. A corresponding advantage can also be achieved inembodiments, in which the electronic module is equipped with a secondconductive-pattern layer, which is located on the opposite surface ofthe base material of the module (on the opposite surface of theinsulation material layer relative to the conductive-pattern layerconnected to the component). The second conductor layer can thus alsoinclude conductive patterns at the location of the component. Theplacing of conductive patterns in the conductor layers at the locationof the component will permit a more efficient use of space in the moduleand a denser structure.

In the following, the invention is examined with the aid of examples andwith reference to the accompanying drawings.

FIGS. 1-8 show a series of cross-sections of some examples ofmanufacturing methods according to the invention and schematiccross-sectional diagrams of some electronic modules according to theinvention.

FIG. 9 shows a cross-sectional view of an electronic module according tothe invention, which includes several installation bases on top of eachother.

In the methods of the examples, manufacturing starts from a conductivelayer 4, which can be, for example, a metal layer. One suitablemanufacturing material for the conductive layer 4 is copper film (Cu).If the conductive film 4 selected for the process is very thin, or theconductive film is not mechanically durable for other reasons, it isrecommended that the conductive film 4 be supported with the aid of asupport layer 12. This procedure can be used, for example, in such a waythat the process is started from the manufacture of the support layer12. This support layer 12 can, for example, an electrically conductivematerial, such as aluminium (Al), steel, or copper, or an insulatingmaterial, such as a polymer. An unpatterned conductive layer 4 can bemade on the second surface of the support layer 4, for example, by usingsome manufacturing method well known in the circuit-board industry. Theconductive layer can be manufactured, for example, by laminating acopper film (Cu) on the surface of the support layer 12. Alternatively,it is possible to proceed by making the support layer 12 on the surfaceof the conductive layer 4.

The conductive layer 4 can also be surfaced with a metal film, or withsome other film including several layers, or several materials. In someembodiments, it is possible to use, for example, a copper film, which issurfaced with a tin or gold layer. In these embodiments, the surfacingtypically comes on the insulating-material-layer 1 side. It is alsopossible to proceed in such a way that the metal film 4 including asurfacing only in the area of the installation of the components 6.

Later in the process, conductive patterns are made from the conductivelayer 4. The conductive patterns must then be aligned relative to thecomponents 6. The alignment is most easily performed with the aid ofsuitable alignment marks, at least some of which can be made already inthis stage of the process. Several different methods are available forcreating the actual alignment marks. One possible method is to makesmall through-holes 3 in the conductive layer 4, in the vicinity of theinstallation areas of the components 6. The same through-holes 3 canalso be used to align the components 6 and the insulating-material layer1. There should preferably be at least two through-holes 3, for thealignment to be carried out accurately.

The connection zones or contact protrusions 7 on the surface of thecomponents 6 are connected to the conductive layer 4, in order to forman electrical contact between the components and the conductive layer 4.The connection can be made using, for example, an ultrasonic orthermo-compression method.

The ultrasonic method then refers to a method, in which two piecescontaining metal are pressed against each other while vibration energyat an ultrasound frequency is brought to the area of the joint. Due tothe effect of the ultrasound and the pressure created between thesurfaces to be joined, the pieces to be joined are bondedmetallurgically. Methods and equipment for ultrasonic bonding arecommercially available. Ultrasonic bonding has the advantage that a hightemperature is not required to form a bond.

The term thermo-compression method refers in turn to a method, in whichtwo pieces containing metal are pressed against each other while thermalenergy is brought to the area of the joint. The effect of the thermalenergy and the pressure created between the surfaces to be joined causethe pieces to be joined to be bonded metallurgically. Methods andequipment for thermo-compression bonding are also commerciallyavailable.

The terms metal layer, metal film, metal contact bump, metal contactzone, and in general a metal item, refer to the fact that themanufacturing material of the item contains enough of at least one metalfor the item to form a metallurgical bond with another item. The itemcan naturally also include several metals as layers, accumulations,zones, or metal alloys. Possible metals include particularly copper,aluminium, gold, and tin.

When attaching the components 6, the components 6 can be aligned totheir planned positions with the aid of alignment holes 3, or otheralignment marks. Alternatively, it is possible to proceed by firstattaching the components 6 to the conductive layer 4 positioned relativeto each other, and after this making the alignment marks alignedrelative to the components 6.

In some embodiments, contact bumps 5, to which the connection zones orcontact protrusions 7 of the components 6 are connected, are made on topof the conductive film 4. In such a method, the contact bumps 5 can alsobe used to align the components 6 during the components' installationstage. The components 6 can, of course, be aligned with the aid of otheralignment marks, for example, the alignment holes 3, if such are made inthe process being used. The contact bumps 5 and the alignment holes 3are then made aligned relative to each other. In embodiments usingcontact bumps 5, the procedure can otherwise correspond to embodimentsin which contact bumps 5 are not used. The use of contact bumps 5 isjustified, for example, if the material of the components' 6 contactzones or contact protrusions 7 is not directly suitable for connectionto the selected material of the conducting layer 4. In that case, thematerial of the contact bumps 5 is selected to permit a bond using thebumps 5 to be created. In such embodiments, the contact bumps 5 are thusintended to match two different conductor materials to each other. Forthis purpose, the contact bump 5 can also be manufactured as a layeredstructure, containing two or more layers of differing materials.

After the connection of the components 6, the space remaining betweenthe components 6 and the conducting layer 4 is filled with a suitablefiller 8. In the examples of the figures, the filler is also spreadaround and on top of the component 6. The filler 8 is usually comepolymer filler. With the aid of the filler 8, the mechanical connectionbetween the component 6 and the conductive layer 4 can be reinforced, sothat a mechanically more durable construction is achieved. The fillermaterial 8 also supports the conductive patterns 14 to be formed laterfrom the conducting layer 4 and to protect the components and the bondbetween the component 6 and the conducting layer 4 during the formationof the conductive patterns 14. In principle, the securing of thecomponent 6 is not, however, an essential operation, especially inembodiments, in which mechanical durability or a long life are notdemanded of the structure. The attachment of the components 6 can beperformed immediately after connection and before the manufacture of theinsulating-material layer 1. Attachment can quite as well also beperformed after the manufacture of the insulating-material layer 1, inwhich case the through-holes made in the insulating-material layer 1 canbe filled with some fuller 8. It is also possible to fill the spaceremaining between the components 6 and the conductive layer 4 with thematerial of the insulating-material layer 1, in which case the substanceforming the insulating-material layer 1 will penetrate under thecomponents 6, in connection with the manufacture of theinsulating-material layer 1. The method can also be modified in such away that the filler 8 is spread on the surface of the component 6 and/orof the conductive layer 4, prior to the attachment of the component 6.In such an embodiment, an electrical connection is thus formed throughthe filler layer 8, so that the filler 8 is displaced from between themetal parts being connected.

A suitable insulating-materia layer 1 is selected as the base materialof the electronic module, for example, the circuit board. Using asuitable method, recesses, or through-holes are made in theinsulating-material layer 1, according to the size and mutual positionsof the components 6 to be attached to the conductive layer 4. Inembodiments in which a filler 8 is used, space is left in the recessesor through-holes for the filler 8 too. The use of the recesses orthrough-holes that are larger than the components 6 is justified inother ways too, because the alignment of the conductive layer 4 with theinsulating-material layer 1 is then not so critical and the danger ofcomponents 6 becoming detached also diminishes. If aninsulating-material layer 1, in which through-holes are made for thecomponents 6, is used in the process, certain advantages can be achievedby using, in addition, a separate insulating-material layer 11, in whichholes are not made. Such an insulating-material layer 11 can be locatedon top of the insulating-material layer 1 to cover the through-holesmade for the components.

If it is desired to make a second conductive layer in the electronicmodule, this can be made, for example, on the surface of theinsulating-material layer 1. In embodiments, in which a secondconductive layer 11 is used, the conductive layer can be made on thesurface of this second conducive layer 11. If desired, conductivepatterns 19 can be made from a second conductive layer 9. The conductivelayer 9 can be made, for example, in a corresponding manner to theconductive film 4. The manufacture of a second conductive film 9 is not,however, necessary in simple embodiments and when manufacturing simpleelectronic modules. A second conductive film 9 can, however, beexploited in many ways, such as additional space for conductive patternsand to protect the components 6 and the entire module againstelectromagnetic radiation (EMC shielding). With the aid of a secondconductive film 9 the structure can be reinforced and warping of theinstallation base, for example, can be reduced.

The manufacturing processes according to the examples can be implementedusing manufacturing methods, which are generally known to those versedin the art of manufacturing circuit boards.

In the following, the stages of the method shown in FIGS. 1-8 areexamined in greater detail.

Stage A (FIGS. 1A and 1B):

In stage A, a suitable conductive layer 4 is selected as the initialmaterial of the process. A layered sheet, in which the conductive layer4 is located on the surface of a support base 12, can also be selectedas the initial material. The layered sheet can be manufactured, forexample, in such a way that a suitable support base 12 is taken forprocessing, and a suitable conductive film for forming the conductivelayer 4 is attached to the surface of this support base 12.

The support base 12 can be made of, for example, an electricallyconductive material, such as aluminium (Al), or an insulating material,such as polymer. The conductive layer 4 can be formed, for example, byattaching a thin metal film to the second surface of the support base12, for example, by laminating it from copper (Cu). The metal film canbe attached to the support base, for example, using an adhesive layer,which is spread on the surface of the support base 12 or metal filmprior to the lamination of the metal layer. At this stage, there neednot be any patterns in the metal film. In the example of FIG. 1, holes 3are made penetrating the support base 12 and the conductive layer 4, foralignment during the installation and connection of the components 6.Two through-holes 3, for example, can be manufactured for each component6 to be installed. The holes 3 can be made using some suitable method,for example, mechanically by milling, impact, drilling, or with the aidof a laser. However, it is not essential to make through-holes 3,instead some other suitable alignment markings can be used to align thecomponents. In the embodiment shown in FIG. 1, the through-holes 3 usedto align the components extend through both the support base 12 and theconductive film 4. This has the advantage that the same alignment marks(through-holes 3) can be used for aligning on both sides of theinstallation base.

FIG. 1B shows an alternative embodiment, in which as in the embodimentof FIG. 1B an installation base, including a support base 12 and aconductive layer 4 on its surface, is made. In the embodiment of FIG. 1Btoo, through-holes 3 used as alignment marks are made in the base. Thiscan be carried out, for example, in the manner shown in FIG. 1A. Unlikethe embodiment of FIG. 1A, in the B modification of the example process(FIG. 1B), contact bumps 5 are made on the surface of the conductivefilm 4. The contact bumps 5 are intended to connect a componentinstalled later to the conductive film 4. In the example process, thecontact bumps are made from some metallurgically compatible material,such a gold (Au). The contact bumps can be manufactured using somesurfacing process generally known in the circuit-board industry.

The contact bumps 5 can be made in the conductive film 4 is someappropriate stage, for example, before making the through-holes 3 orother alignment marks. In that case, the contact bumps 5 are alignedrelative to each other while to the alignment marks, such asthrough-holes 3, of the alignment-mark making stage are aligned relativeto the contact bumps 5. Another alternative is to make the alignmentmarks first and make the contact bumps 5 after this in the selectedpositions, with the aid of the alignment marks.

Stage A can also be performed in the same way in embodiments in which aself-supporting conductive layer 4 is used and from which the supportlayer 12 is thus totally missing.

Stage B (FIGS. 2A, 2B, and 2C):

Three modifications of stage B are shown. In the A modification (FIG.2A), a component 6, which includes contact bumps 7 in the connectionzones of the component, is attached to the conductive layer 4. Thecontact bumps 7 of the component are connected to the conductive layer 4in such a way that an electrical contact is created between the contactbump 7 and the conductive layer 4. It would be good for the connectionto also withstand mechanical stress, so that the connection will not beeasily broken in later process stages, or during the operation of theelectronic module. The connection is formed using a suitable connectionmethod, for example, the ultrasonic and thermo-compression methods. Inthe connection stage, the through-holes 3 made for alignment, or otheravailable alignment marks are used to align the component 6.

In the B modification (FIG. 2B) too, a component 6, which includescontact bumps 7 in the connection zones of the component, is connectedto the conductive layer 4. The difference to the A modification is that,in the B modification, contact bumps 5 are also formed on top of theconductive layer 4. The contact bumps 7 of the component are thenconnected to the contact bumps 5 of the installation base. Theconnection can, as in modification A, be formed using a suitableconnection method, for example, the ultrasonic or thermo-compressionmethods. In the B modification, the component can be aligned, accordingto the embodiment, using the contact bumps 5, the through-holes 3, orother alignment marks suitable for alignment.

In the C modification of the example process, as in the B modification,an installation base is used, in which contact bumps 5 are made on topof the conductive layer 4. Unlike in the A and B modifications, in the Cmodification a component 6 is used, the surface of which has flatcontact zones, but no actual contact bumps 7, or other correspondingcontact protrusions. In the C modification, connection and alignment arecarried out as in the B modification, except that the connection isformed between the conductive material of the contact zones and thecontact bumps 5 of the installation base. In the following figures, theC modification will be presented in connection with the A modification,as from the point of view of the following process stages, it is of nosignificance whether the contact bumps are formed of the surface of thecomponent 6 (contact bumps 7), or of the conductive layer 4 (contactbumps 5).

Stage C (FIGS. 3A and 3B):

In stage E, filler 8 is placed under the component 6, by means of whichthe space remaining between the component 6 and the conductive layer 4is filled. The filler can also be spread around and on top of thecomponent 6, as is done in the embodiments of FIGS. 3A and 3B. Thefiller 8 can be, for example, some suitable polymer. For example, epoxyfilled with suitable particles can be used as the polymer. The polymercan be spread using, for example, some known vacuum-paste-pressingdevice suitable for the task. The purpose of the filler 8 is to securethe component 6 mechanically to the conductive layer 4, so that theelectronic module will better withstand mechanical stress. In addition,the filler 8 protects the component 6 during later process stages.Protecting the component 6 can be particularly beneficial inembodiments, in which conductive patterns are formed by etching theconductive layer 4 and in which the surface of the component 6 issensitive to the effect of the etching agent used. Otherwise, thesecuring of the component is in no way essential and, at least in someembodiments, stage C can be omitted or performed at a later stage in theprocess.

Stage D (FIGS. 4A and 4B):

In stage D, an insulating-material layer 1, in which there arepre-formed cavities 2 or recesses for the components 6 to be attached tothe conductive layer 4, is placed on top of the conductive layer 4. Theinsulating-material layer 1 can be made from a suitable polymer base, inwhich cavities or recesses according to the size and position of thecomponents 6 are made using some suitable method. The polymer made canbe, for example, a pre-preg base known and widely used in thecircuit-board industry, which is made from a glass-fibre mat andso-called b-state epoxy.

When manufacturing a very simple electronic module, theinsulating-material layer 1 can be attached to the conductive layer 4 inconnection with stage D and the process continued with the patterning ofthe conductive layer 4.

Stage E (FIGS. 5A, 5B, 6A, and 6B):

In stage E, an unpatterned insulating-material layer 11 is placed on topof the insulating-material layer 1 and on top of it a conductive layer9. Like the insulating-material layer 1, the insulating-material layer11 can be reinforced with a suitable polymer film, for example, theaforesaid pre-preg base. The conductive layer 9 can, in turn, be, forexample, a copper film, or some other film suitable for the purpose.After this, the layers 1, 11, and 9 are pressed with the aid of heat andpressure in such a way that the polymer (in the layers 1 and 11) formeda unified and tight layer between the conductive layer 4 and 9 aroundthe components 6 (see FIGS. 6A and 6B). The use of this procedure makesthe second conductive layer 9 quite smooth and even.

When manufacturing simple electronic modules and those including asingle conductive-pattern layer 14, stage E can even be totally omitted,or the layers 1 and 11 can be laminated to the construction, without aconductive layer 9.

Stage F (FIGS. 7A and 7B):

In stage F, the support base 12 is detached or otherwise removed fromthe construction.

Removal can take place, for example, mechanically or by etching. Stage Fcan naturally be omitted from embodiments that do not employ a supportbase 12.

Stage G (FIGS. 8A and 8B):

In stage G, the desired conductive patterns 14 and 19 are formed fromthe conductive layers 4 and 9 on the surface of the base. If only asingle conductive layer 4 is used in the embodiment, the patterns areformed on only one side of the base. It is also possible to proceed insuch a way that the conductive patterns are only formed from theconductive layer 4, even though a second layer 9 is also used in theembodiment. In such an embodiment, the unpatterned conducive layer 9 canact, for example, as a mechanically supporting or protective layer ofthe electronic module, or as a protection against electromagneticradiation.

The conductive patterns 14 can be made, for instance, by removing theconductive material of the conductive layer 4 from outside of theconductive patterns. The conductive material can be removed, forexample, using one of the patterning and etching methods that are widelyused and well known in the circuit-board industry. If the conductivelayer 4 is made from a special material, the conductive patterns 14 canalso formed in such a way that the conductivity of the conductivematerial 4 is removed from outside of the conductive patterns, forexample, with the aid of electromagnetic radiation. When using aconversely reactive material, the material is put into a conductivestate in the area of the conductive patterns. Thus, the conductive layer4 is, in the previous stages of the method, actually the insulatinglayer, which can be converted to be conductive with the aid of specialtreatment. The manner of forming the conductive patterns 14 is thus not,as such, essential to the manufacture of the electronic module.

If through-holes 3 are made in the embodiment, the conductive patterns14 to be made from the conductive layer 4 can be aligned with the aid ofthe through-holes 3. The conductive patterns 19 made from the conductivelayer 9 can also be aligned with the aid of through-holes 3, though thealignment must then be performed from the opposite side of the base.

After stage G, the electronic module includes a component 6, or severalcomponents 6 and conductive patterns 14 and 19 (in some embodiments onlyconductive patterns 14), with the aid of which the component orcomponents 6 can be connected to an external circuit, or to each other.The conditions for manufacturing a functional totality then existalready. The process can thus be designed in such a way that theelectronic module is already finished after stage G and FIGS. 8A and 8Bshow examples of some possible electronic modules that can bemanufactured using the example methods. Of course, if it is wished, theprocess can also continue after stage G, for example, by surfacing theelectronic module with a protective substance, or by making additionalconductive patterns on the first and/or second surface of the electronicmodule.

FIG. 9

FIG. 9 shows a multi-layered electronic module, which includes threebases 1 laminated on top of each other, together with their components6, and a total of six conductive-pattern layers 14 and 19. The bases 1are attached to each other with the aid of intermediate layers 32. Theintermediate layer 32 can be, for example, a pre-preg epoxy layer, whichis laminated between the installation bases 1. After this, holes runningthrough the module are drilled in the electronic module, in order toform contacts. The contacts are formed with the aid of a conductivelayer 31 grown in the holes. With the aid of the conducts 31 runningthrough the electronic module, the various conductive-pattern layers 14and 19 of the installation bases 1 can be suitably connected to eachother, thus forming a multi-layered functioning totality.

On the basis of the example of FIG. 9, it is clear that the method canalso be used to manufacture many different kinds of three-dimensionalcircuit structures. The method can be used, for example, in such a waythat several memory circuits are placed on top of each other, thusforming a package containing several memory circuits, in which thememory circuits are connected to each other to form a single functionaltotality. Such packages can be termed three-dimensional multichipmodules. In modules of this kind, the chips can be selected freely andthe contacts between the various chips can be easily manufacturedaccording to the selected circuits.

The sub-modules (bases 1 with their components 6 and conductors 14 and19) of a multi-layered electronic module can be manufactured, forexample, using one of the electronic-module manufacturing methodsdescribed above. Some of the sub-modules to be connection to the layeredconstruction can, of course, be quite as easily manufactured using someother method suitable for the purpose.

The examples of FIGS. 1-9 shows some possible processes, with the aid ofwhich our invention can be exploited. Our invention is not, however,restricted to only the processes disclosed above, but instead theinvention also encompasses various other processes and their endproducts, taking into account the full scope of the claims and theinterpretation of their equivalences. The invention is also notrestricted to only the constructions and method described by theexamples, it being instead obvious to one versed in the art that variousapplications of our invention can be used to manufacture a wide range ofdifferent electronic modules and circuit boards, which differ greatlyfrom the examples described above. Thus, the components and wiring ofthe figures are shown only with the intention of illustrating themanufacturing process. Thus many alterations to and deviations from theprocesses of the examples shown above can be made, while neverthelessremaining within the basic idea according to the invention. Thealterations can relate, for example, to the manufacturing techniquesdescribed in the different stages, or to the mutual sequence of theprocess stages.

With the aid of the method, it is also possible to manufacture componentpackages for connection to a circuit board. Such packages can alsoinclude several components that are connected electrically to eachother.

The method can also be used to manufacture total electrical modules. Themodule can also be a circuit board, to the outer surface of whichcomponents can be attached, in the same way as to a conventional circuitboard.

1. A method for manufacturing an electronic modules, the method comprising: taking a metallic conductive layer, taking a component, which has a contacting surface, which has metallic contact zones, connecting the component to the first surface of the conductive layer by an ultrasonic or thermo-compression method, in such a way that metallurgical joints and at the same time electrical contacts are formed between the conductive layer and the contact zones of the component, making, on the first surface of the conductive layer, an insulating-material layer, which surrounds the component connected to the conductive layer, and making conductive patterns from the conductive layer.
 2. A method according to claim 1, in which the metallurgical joints are formed by connecting the contact zones to the conductive layer directly and without interfacing medium.
 3. A method according to claim 1, in which the contact zones are metal and in which, prior to the formation of the electrical contact, metal contact bumps are grown on top of the conductive layer, and in which the metallurgical joints are formed via contact bumps by connecting the contact zones metallurgically to the contact bumps.
 4. A method according to claim 1, in which the conductive layer is metal and, prior to the formation of the electrical contact, metal contact bumps are grown on top of the contact zones of the component, and in which the metallurgical joints are formed via contact bumps by connecting the contact bumps metallurgically to the conductive layer.
 5. A method according to claim 2, in which the metallurgical connection is implemented solderlessly.
 6. A method according to claim 1, in which at least one alignment mark is made on the installation base, for the alignment of a component, and the component is set in the installation hole, aligned relative to at least one alignment mark.
 7. A method according to claim 6, in which at least one alignment mark is a through hole, which penetrates the conductive layer.
 8. A method according to claim 7, in which the conductive patterns are aligned relative to the component, with the aid of at least one through hole.
 9. A method according to claim 1, in which the space between the component and the conductive layer is filled with a filler, for example, a polymer.
 10. A method according to claim 1, in which conductive patterns are made from the conductive layer of the installation base by removing part of the material of the conductive layer, so that the remaining material forms conductive patterns.
 11. A method according to claim 1, in which a support layer is attached to the conductive layer, and is removed after the manufacture of the insulating-material layer, but before the manufacture of the conductive patterns.
 12. A method according to claim 1, in which the insulating-material layer surrounding the component is manufactured by attaching an insulating-material layer, in which cavities or recesses for a component or components are made, to the conductive layer.
 13. A method according to claim 12, in which a second insulating-material layer, which is unified and which covers the component, is attached to the surface of the first insulating-material layer attached to the conductive layer.
 14. A method according to claim 1, in which a second conductive-pattern layer is manufactured on the opposite surface of the insulating-material layer.
 15. A method according to claim 1, in which more than one component is embedded in the electronic module in a corresponding manner.
 16. A method according to claim 15, in which conductive patterns are made from the conductive layer, in such a way that, by means of the conductive patterns, an electrical connection is formed between at least two components.
 17. A method according to claim 15, in which the components embedded in the base are connected electrically to each other, in order to form a functioning totality.
 18. A method according to claim 1, in which a first module is manufactured along with at least one second module and the manufactured modules are attached to each other one on top of the other, so that the modules are aligned relative to each other.
 19. A method according to claim 18, in which holes for feed-throughs are made through the modules that are attached on top of each other and conductors are made in the holes thus created, in order to connect the electronic circuits on each of the moduless to each other to form a functional totality.
 20. An electronic module, which includes an insulating-material layer, which has a first surface and a second surface, at least one cavity or recess in the insulating-material layer, which opens out onto the first surface, at least two components inside the at least one cavity or recess, which components include contact zones on that side of the component that faces the first surface of the insulating-material layer, and which components are positioned in such a way that the contact zones are located at a distance from the level of the first surface of the insulating-material layer, a first conductive-pattern layer, which contains at least one metal and runs on the first surface of the insulating-material layer and extends on top of the at least one cavity or recess in the insulating-material layer at the location of the contact zones of the components, contact bumps for forming electrical contact between the first conductive pattern layer and the contact zones of the component, which contact bumps contain at least one metal, and a second conductive-pattern layer, which runs on the second surface of the insulating-material layer and by means of feed-throughs connects to the first conductive-pattern layer to connect the components as a functional entity, and in which module the contact bumps metallurgically and solderlessly connect to the first conductive-pattern layer substantially at the level of the first surface of the insulating-material layer.
 21. An electronic module, which includes an insulating-material layer, which has a first surface and a second surface, at least one cavity or recess in the insulating-material layer, which opens out onto the first surface, at least two components inside the at least one cavity or recess, which components include contact zones substantially at the level of the first surface of the insulating-material layer, the contact zones containing at least one metal, a first conductive-pattern layer, which contains at least one metal and runs over the first surface of the insulating-material layer and extends on top of the at least one cavity or recess in the insulating-material layer, and a second conductive-pattern layer, which runs on the second surface of the insulating-material layer and by means of feed-throughs connects to the first conductive-pattern layer to connect the components as a functional entity, and in which module the first conductive-pattern layer metallurgically and solderlessly connects to the contact bumps of said at least one component substantially at the level of the first surface of the insulating-material layer.
 22. An electronic module according to either claim 20, in which the thickness of the component is less than the thickness of the insulating-materia layer in the direction between the first surface and the second surface of the insulating-material layer.
 23. An electronic module according to claim 20, in which the cavity or recess contains a filler material between the component and the insulating-material layer, for securing the component to the insulating-material layer.
 24. An electronic module according to claim 20, in which the said conductive-pattern layer is essentially flat, so that that surface of the conductive-pattern layer that lies against the insulating-material layer and the cavity or recess in the insulating-material layer for the component, is located entirely at essentially the level of the first surface of the insulating-material layer.
 25. An electronic module according to claim 20, in which the cavity or recess extends through the whole insulating-material layer in the direction between the first surface and the second surface of the insulating-material layer.
 26. An electronic module according to claim 20, wherein the second conductive layer includes conductive-patterns at the location of the component in the cavity or recess. 